1. Field of the Invention
The present invention relates to a laminated group III nitride semiconductor wafer and a group III nitride semiconductor device.
2. Related Background Art
Literature 1 discloses a high electron mobility transistor (HEMT). In the HEMT disclosed in Literature 1, an AlN layer (50 nm), an Al0.06Ga0.94N layer (100 nm), an Al0.06Ga0.94N layer (450 nm) for a channel layer, and an Al0.31Ga0.69N layer (25 nm) for a barrier layer are laminated in sequence on an SiC substrate. Literature 1 states that a channel layer including AlGaN in the HEMT causes alloy scattering to lower the electron mobility.
Literature 2 discloses a HEMT. In the HEMT disclosed in Literature 2, an AlN buffer layer, an AlGaN channel layer, and an AlGaN barrier layer are laminated in sequence on a sapphire substrate.    Literature 1: Ajay RAMAN et al., Japanese Journal of Applied Physics, Vol. 47, No. 5, pp. 3359-3361 (2008)    Literature 2: Takuma Nanjo et al., Applied Physics Letters, Vol. 92, 263502 (2008)